Populus

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Populus tremuloides “Quaking Aspen” Salicaceae

Apgar Lookout Trail, Glacier National Park, MT
October 9, 2015
Robert Niese

This adorable Quaking Aspen sapling had lost all but three of its leaves by the time I photographed it in early October. While Quaking Aspen is famous for its adventitious, clonal reproduction, this little guy probably grew from seed because it was all alone in the at the edge of a stand of conifer saplings. Seedlings in the genus Populus are often the first to colonize abandoned mining sites that are too toxic for other species. Recent research suggests that they are only capable of this feat because of a mutualistic relationship with various species of mycorrhizal fungi such as these earthballs.

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Populus trichocarpa

Populus trichocarpa “Black Cottonwood” Salicaceae

Clark Fork Natural Area, Missoula, MT
October 23, 2014
Robert Niese

The brilliantly yellow trees lining our valley bottoms and riversides here in the Pacific Northwest are predominantly Black Cottonwoods (also known as Western Basalm Poplars). They are famous for their fluffy, cotton-coated seeds which fill our air and waterways throughout the early summer. These seedlings need moist, bare soil to germinate and will rapidly colonize riverbanks exposed by erosion. Seedlings become dominant, fully-grown trees after about 25 years making them ideal for cultivation both in farms for harvest and as ornamentals in neighborhoods. Unfortunately, they also rarely live more than 150 or 200 years, so many neighborhoods in our area (many of which were first constructed in the 1800s) are being forced to remove these dying giants.

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Apgar, Glacier National Park - by Robert NieseGoat Lick, Glacier National Park - by Robert NiesePopulus Leaf, Glacier National Park - by Robert NieseApgar, Glacier National Park - by Robert Niese   Two Medicine, Glacier National Park - by Robert NieseApgar, Glacier National Park - by Robert Niese

Fall is in full swing here in Montana!

I made it up to Glacier National Park this weekend to experience some fall foliage firsthand. It was absolutely stunning!

Here’s a brief guide to foliage colors in Western Montana!

Yellow:

  • Members of Salicaceae (Cottonwoods, Aspens, Poplars, Willows) and Betulaceae (Alders, Birch) dominate the yellow palate of our PNW hillsides. These species begin turning in September and their colors will persist, depending on rain and wind, until late October.
  • Larch (Larix) is our only deciduous conifer in the PNW. Depending on elevation, Larch will begin turning between the first and third weeks of October.
  • Bracken Fern (Pteridium aquilinum) and Thimbleberry (Rubus parviflorus) also maintain a substantial degree of yellowness early in the fall before turning pale brown in October.

Red:

  • Red fall foliage in western Montana is largely restricted to the understory.
  • Ericaceous shrubs such as Huckleberries (Vaccinium) change color depending on sun exposure. On exposed hillsides, they’ll be red before August, while in dense forests, they may only begin changing in October.
  • Rosaceous shrubs such as Oceanspray (Holoduscus), Ninebark (Physocarpus), Spiraea, Hawthorn (Crataegus), and Rose (Rosa) also tend to go through a red phase in their color change. While some of these species appear to start early (September), most of their change will persist well into October and even November.
  • Red-osier Dogwood (Cornus sericea) has an interesting color change. Here in the riparian areas of Western Montana, they appear to go through a green and maroon phase, which is quite lovely, before losing their leaves entirely. Fortunately, even after losing their leaves, these shrubs have phenomenal red stems that definitely supplement the colors of fall.
  • Maple (Acer) also go through a red phase here in western Montana. These native species appear to have dropped most of their leaves by mid-October.

Species with little color change:

  • I’ve noticed several dominant deciduous trees and shrubs that don’t appear to change color considerably with the seasons. Of these, Ceanothus and Symphoricarpos are the most abundant.
  • Ceanothus tends to keep its green foliage throughout the year or turn straight to brown in the fall.
  • Snowberries (Symphoricarpos) appear to do a variety of things, but here in western Montana, they generally drop their leaves quickly without much ado.
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Populus tremuloides “Quaking Aspen” Salicaceae

Council Grove State Park, MT
March 16, 2015
Robert Niese

We have several species of willows, aspens (well, one aspen), and poplars in the PNW that produce these adorable fuzzy flowers in the early spring. These compact “pussy-foot” catkins are very typical of willows (Salix), but Quaking Aspen produces a very similar inflorescence. The easiest way to tell the two apart is to look at the buds. In Aspen, you’ll see lots of overlapping bud scales while in willows, the buds are smooth and consist of a single, wrap-around scale.